The present invention relates to a method for identifying and quantifying polymers in aqueous systems by utilizing immunoassay techniques. In particular, monoclonal antibodies ("MAbs") are created against: an initiator (or fragment thereof) used to start the polymer process; a chain transfer agent used in the polymerization process to prepare the polymer being detected; or a functional group which can be subsequently attached to a chain transfer agent. The present invention also relates to new hybridomas (immortalized cell lines) which express these MAbs. The present invention is particularly useful for determining the concentration of polymers used in water treatment applications.
Water-soluble polymers are used in many aqueous systems, for example: as mineral dispersants; as water-treatment additives for boiler waters, cooling towers, reverse osmosis applications, sugar refining, paper production, geothermal processes, and oil wells; and as detergent additives acting as builders, anti-filming agents, dispersants, sequestering agents, and encrustation inhibitors. In these types of applications, the polymers complex with minerals or other substances to remove them from the water, for example, to prevent corrosion and mineral deposits (scale) in water-treatment applications. Over time, as the complexation sites on the polymer become saturated, the polymer becomes inactivated or decomposes, and more active polymer must be added. This is particularly important in water-treatment applications, where insufficient active polymer can result in the water treatment being overwhelmed by dissolved minerals, causing severe corrosion or scale deposits, and where maintenance of a higher than necessary active polymer concentration is costly and inefficient. It is therefore desirable to be able to detect readily the polymer concentration within a system at various times, in order to determine whether or not additional polymer should be added.
One of the problems associated with detecting polymers in aqueous systems is the lack of sensitivity in traditional detection methods such as calorimetric or fluorimetric assays, since the polymers are generally present at very low levels, from 500 down to less than 5 parts per million ("ppm"). Another problem associated with detecting polymers in aqueous solutions is that the detection methods frequently lack selectivity and may give false results for components of the aqueous system other than polymers.
Attempts to overcome these problems have included methods for manufacturing MAbs against portions of the product polymers, then using these MAbs to detect the presence or concentration of product polymer using immunoassay techniques. Such methods are disclosed and discussed in, for example, EP 540 314 A1 (Wetegrove, et al.), EP 535 347 A2 (Wetegrove, et al.), and EP 559 249 A1 (Weatherby, et al.). In all of these methods, the MAbs bind to selected sites on the polymer, but one-to-one correspondence between the MAb and a particular polymer strand is unlikely due to the great number of repeating units within a polymer chain; moreover, since the polymers are of varying chain lengths, there will be a variation in the number of MAbs binding to each polymer. Thus, determination of MAb to polymer concentration ratio will be batch dependent (i.e., the ratio will vary depending on the particular batch of polymer prepared), and accuracy of such measurements may vary relatively widely.
PCT US94/09264 (Garner, et al.) discloses a method for marking products for later identification. This method involves creating a low molecular weight hapten, covalently bonding such hapten to a carrier compound, and associating such hapten-labeled compound with the product, such that the hapten serves as a marker which can later be detected using immunoassay techniques. The carrier compound can be a polymer, such that the hapten is either attached to the already formed polymer, or the hapten can be attached to the monomer prior to polymerization. To be useful in this method, a hapten-labeled compound (the "marker compound") is non-deleterious to the product, is inert with respect to the product, and is not already be associated with the product. The marker compound is generally associated with the product by mixing the marker compound with product, but it can be present in the product packaging or labeling.
Although Garner, et al. disclose that the "use of this tagged compound in a fixed ratio to untagged compound allows for tracing of the tagged compound," the nature of their method precludes quick and convenient determination of product concentration where the product is a polymer. Garner, et al. teach that the hapten can be attached to the already formed polymer, or to the monomer prior to polymerization; however, in either case, it will not be possible to determine absolutely the hapten:polymer ratio, since the length of each polymer chain is not constant, and the number of haptens attached to each particular polymer chain will vary. Thus, the hapten:polymer ratio will be batch-dependent, making detection of polymer concentration difficult: standard concentration curves will have to be run for each batch of tagged polymer; the polymer added to the system is unlikely to be from the same batch as the previously added polymer, possibly affecting the calibration and accuracy of the assay; and the total polymer concentration in a system will likely be composed of polymers from various batches rather than only one batch, also possibly affecting the calibration and accuracy of the assay.